LibWeb: Extract CanvasState class from CRC2D

As with CanvasPath, this is to better match the spec IDL.

Userland/Libraries/LibWeb/HTML/Canvas/CanvasState.cpp

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
+ * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/HTML/Canvas/CanvasState.h>
+
+namespace Web::HTML {
+
+// https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-save
+void CanvasState::save()
+{
+    // The save() method steps are to push a copy of the current drawing state onto the drawing state stack.
+    m_drawing_state_stack.append(m_drawing_state);
+}
+
+// https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-restore
+void CanvasState::restore()
+{
+    // The restore() method steps are to pop the top entry in the drawing state stack, and reset the drawing state it describes. If there is no saved state, then the method must do nothing.
+    if (m_drawing_state_stack.is_empty())
+        return;
+    m_drawing_state = m_drawing_state_stack.take_last();
+}
+
+// https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-reset
+void CanvasState::reset()
+{
+    // The reset() method steps are to reset the rendering context to its default state.
+    reset_to_default_state();
+}
+
+// https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-iscontextlost
+bool CanvasState::is_context_lost()
+{
+    // The isContextLost() method steps are to return this's context lost.
+    return m_context_lost;
+}
+
+}